‘New standards needed’ to deal with light’s effect on our body clocks

Vitamin D on tap: is it unnatural to spend so much time indoors and what can artificial lighting do to help our bodies?

The effect of light on the body should be recognised in updated lighting standards and guidelines, said experts at LuxLive this week.

Christian Cajochen of the University of Basel explained ways to measure and quantify how lighting influences our bodies. Cajochen’s research focuses on the ‘non-visual’ effects of light – such as the impact that light has on the body clock, alertness and sleep.

Cajochen said Thomas Edison was wrong when he claimed that light does not affect our health and sleep. In fact, light impacts our circadian rhythms more powerfully than any drug.

In the lab, circadian rhythms can be quantified by looking at the secretion of the hormone melatonin, he explained, before describing how lighting has been proven to affect our alertness and our sleep quality. We sleep less deeply following excessive light exposure, especially in the evening.

Research has found that blue-enriched light from TV sets, computers and tablets in the evening and early in the night can elicit an alerting response and delay the circadian response, he said. This can decrease sleep quality and delay the time taken to fall asleep. He pointed, too, to the fact that the risk of insomnia is greater in older people, so there are ‘trade-offs’ between visual and non-visual effects of light.

“We are now trying to implement this into lighting designs, codes and standards,” Cajochen added.

We’ve got used to a very static lighting scheme at work and we don’t like it. We’ve all become zombies"

Helen Loomes, Trilux

So how can we bring human-centric lighting into the real world?

Helen Loomes of lighting manufacturer Trilux suggested that organisations and individuals can take small steps to harness more human-centric lighting, such as modifying shift patterns. “A lot is down to how we use the information we have,” she said. “We’ve got used to a very static lighting scheme at work and we don’t like it. We’ve all become zombies. You can use products in different ways, even though we cannot mimic daylight.”

“It really affects how we feel,” she said – pointing to the power of lighting to make an environment feel ‘invigorating’ or ‘depressing’.

And, mocking many manufacturers’ claims to produce human-centric lighting, lighting designer John Bullock said that we live an ‘unnatural’ life in the post-industrial north and west, spending so much of our lives indoors under artificial light. “Cynically, the buyers are looking for maximum productivity,” he added.

Others were more positive. Reine Karlsson of Lund University, for instance, stated that we now have the possibility to vary intensity and colour composition in a way which was not possible with traditional lights. “We have more knowledge of what to do and what not to do,” he said.

Comments
1

Gerry Wootton

03 Dec 2015

Again with the 'blue light' thing. All light of sufficient intensity causes LIMS (light induced melatonin supression). The evidence for blue light being more active is limited and mostly flawed: first, many researchers assume that photopic light levels are relevant to biological response and, worse, rely on instrumentation that lacks gauge capability for shorter wavelengths or even worse use assumed data or equally worse assume that CCT describes SPD exactly; second, almost none actually measure spectral power distribution or compensate for measured biological response or worse use constrained (non-white) sources; third, very few studies are from real life experience or even replicate real life experience, worse, some even employ chemical dilaters and other highly artificial methods; fourth, the majority of sample populations fall into the 18-28 year age range and worse, exclude potential subjects with imperfect vision; fifth, most studies extrapolate dark adapted conditions from higher light level conditions even though it is well know that not only response but photophor mechanisms vary at low light levels, worst case extrapolating across physiological discontinuities.
An example: a study that indicated an elevated sensitivity to blue used two cohorts of subjects one equipped with band-pass lenses to eliminate short wavelength light but also longer wavelength light; in addition to not permuting samples, no correction was applied for something as simple as the reduction of intensity resulting from removing portions of the SPD or even the first surface reflection loss and vignetting caused by glasses; as common, no effective SPD was measured for each case and additionally it was assumed that visual response is synonymous with physiological response. In other words, it is impossible to determine whether light intensity, spectrum or sampling was a factor - one would expect at least and ANOVA and at least one control group (this is pretty basic DOE).
If one considers the results from various experiments that attempt to determine the function for LIMS versus light levels, agreement is very poor: one can find data indicating 50% LIMS at anywhere from 100 to 300 lux - 200+/-100 cannot be considered reproducible results. Another problem is that being awake, as is required to achieve optical exposure also has an effect on bio-rhythms which only a few studies control for. For sure, based on biological response alone, one cannot extrapolate data obtained at 100 lux or more to levels below 20 lux as many choose to do - fanciful thinking!

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